This invention relates to providing systems for improving the operational performance of bulk shipping containers. More particularly this invention provides a system comprising specially adapted shipping container liners that are self-supporting, without the need of rear mounted rigid supportive bars, to retain the liner within the shipping container during filling. In addition, this invention provides an improved discharge hopper adapted to receive bulk material at an increased rate, appropriately matching the increased discharge rates of the fore-mentioned liner.
Container liners are large bag-like structures adapted to -fit within the interior of sea containers, truck trailers, and similar cargo-holding enclosures. They are used primarily to provide a clean and safe environment for the bulk transportation of industrial and agricultural products. These products commonly include minerals, powders, plastic pellets, rice, coffee beans, flour and grains, etc.
Typically, the container liner is loosely hung within the interior of the container. The bottom front of the liner is typically secured by a steel bar that slips through a sleeve, centered across the width of the liner, and loops made with strap material, sewn on either side of the liner (in line with the sleeve). The steel bar is then fitted into slots built into both sides of the front of the container. The back of the liner (located at the rear of the container near the access doors) comprises ports and chutes sewn into the upper and lower portions of the line. These ports and chutes are used to fill and discharge cargo. To prevent the liner from deflecting (bulging) out of the back of the container during filling, three to five steel bars are typically hung, in a horizontal position, on the back of the liner. Typically, the steel bars are supported by belt-loops sewn onto both sides of the rear of the liner, proportionally spaced from the top to the bottom. The bar ends are engaged in slots provided on either side of back of the container. These steel bars allow the container doors to be closed after filling, and function to hold the cargo-filled liner inside the container during the discharge of the product.
To discharge the product from the liner, the entire container is typically tipped like a dump truck. During the discharge operation, the steel bars act as a safety shield to prevent the liner from falling out of the container under the considerable weight of the stored cargo. Container liners now require these steel bars to be mounted in the rear of the container prior to filling. They are typically shipped with the container and are discarded after the container is emptied. The economic and environmental cost of using a new set of steel bars with each shipment is substantial.
A further significant problem associated with the use of conventional liners is the inconsistent placement of the liner within the interior of the container. Typically, the lower floor panel within the interior of the liner develops folds as the liner is installed, loaded, and unloaded. Existing liner systems do not provide means for smoothing and flattening the interior of the liner flat prior to use. Furthermore, existing liner systems do not maintain the interior of the liner in a flattened arrangement during product filling and discharge. Folds occurring within the interior of the liner typically slow the discharge of product as the containers are tipped, and often trap portions of the product that remains as residue within the liner.
A similar condition occurs within the discharge hopper as the liner chute develops folds and tears within the hopper's interior during discharge. Typically, this trapped product is lost and discarded along with the liner. In a large shipment, lost product may amount to several hundred pounds of residue material. Once again, the loss of product during the use of conventional liner systems has both economic and environmental implications.
Clearly, a need exists for improved container liners reducing waste associated with the retention of the liners within the containers using steel bars and the loss of product due to inconsistent and uneven placement of the liners within the containers. Furthermore, a need exists for improved discharge hoppers that facilitate rapid and complete discharge of materials.